Method of reshaping fibrous filter rods



April 11, 1961 R. M HENRY METHOD OF RESI-IAPING FIBROUS FILTER RODS 2 Sheets-Sheet 1 Filed March 9, 1956 wmwmE ..zo z 92 292E April 11, 1961 R. M HENRY 2,979,433

METHOD OF RESHAPING FIBROUS FILTER RODS Filed March 9, 1956 2 Sheets-Sheet 2 74 82 E22 3 M -/Q METHOD OF RESHAPING FIBROUS FILTER nous Richard MacHenry, Prospect Park, Pa., assignor'to American Viscose Corporation, Philadelphia, 'Pa., a corporation of Delaware Filed'Mar. 9, 1956, s em. 570,590 3. Claims. c1. "154-91 nited States Patent travelling through the reshaping device;

described a method (described herewithin also) for pro-.

ducing a relatively stifi absorbent filter element up to the stage at which the element is collectedin package or wound form ready foruse' by the cigarette manufacturer. The cigarette manufacturer would prefer to make his own filters, but he does not want to go into the textile business which would require such textile operations as picking and carding of fibrous material .when the filter material is to be formed of textile fibers. It is therefore desirable for an outside producer to produce the filter material and transport it to the cigarette com: panies. While engaged in this practice,, it was found that when the continuous filter rod or cylinder was collect'ed in wound or coiled package form, they preferred form for shipment, the filter cylinder became flattened or otherwise distorted from its original shape. This flattened condition occurred as a result of the tension applied to the continuous filter rod during the wind-up operation, the bending of the cylinder during the windup and the weight of the upper layers or convolutions of filter material as exerted upon the lower orinner layers.

Upon receipt of the continuous filter materialiby the cigarette manufacturer, it was foundthat-the. continuous filter rod couldnotbe used in the filter rod forming machines because of its flattened or distorted condition.

It is therefore one object of my invention to provide a new and improved method for producing a porous, absorbent element of synthetic fibers wherein the element is reshaped to'its original cylindrical form after being flattened during collection of the material in package form. Y 7 i -Another object of my invention is to provide anew and improved method for producing a continuous, porous and absorbent element of synthetic fibers which element may be used as cigarette filter material wherein the flat= tened or distorted element in package form is reshaped to its original cylindrical form as it is unwound from its package. f

Further objects and advantages of my invention will become more apparent from a study of the, following de- I seription and drawings wherein:

Figure 1 is a view of the fibrous element in bundle or sliver.form; I I i Figure 2 is a perspective of reduced scale of my tobacco smoke filter} i Y Figure 3 is a perspective of a filter type cigarette with my tobacco smoke filter incorporated therein;

Figure 4 is a schematic side view of the apparatus for along lines V-V Figure 7 is a side view, partially sectioned, 'of the re-,

shaping device showing the continuous fibrous element Figure 8 is a section taken along lines VIII-VIII of Figure 7;

Figure 9 is a perspective of a length .of the fibrous element showing the element in its flattened or distorted condition resulting from collecting the element in wound or coiled package form; and

Figure 10 is a perspective of -a short length of the fibrous element after it has been discharged from the reshaping device.

Generally, my method for forming the fibrous vabsorbent element comprises thesteps of first forming a sliver or bundle of a mixture of non-adhesive fibers and potentially adhesive fibers. The formed sliver is then passed through an activating chamber wherein the potentially adhesive fibers are activated to an adhesive condition. The sliver is. compressed as it is discharged from the activating chamber wherebyxthe fibers are bonded together. The sliver is then collected in a coiled :package on a .wind-up spool or other suitable wind-up element during It will be understood that throughout'the following specification and claims, the terms non-adhesive and potentially adhesive refer to'types of fibers,,one of,

which becomes tacky or adhesive under conditionsunder which the other'fiber is relatively unaffected. Where the tacky or adhesive condition results from elevated temperature, the potentially adhesive fibers will, of course,-

be of a thermoplastic nature. Ordinarily, the non-adhesive fiber will not be thermoplastic-but a thermoplastic fiber could be used provided the temperature atI-which it became tacky is sufliciently higher than the temperature at which the other potentially adhesive fiberbecom'es tacky. By way of example, the potentially adhesive fibers are 'formed from vinyl resins resulting from the polymerization of compounds containing the'vinyl group such as polyvinylchloride or copolymers of vinyl chloride and vinyl acetate. Other potentially adhesive fibers, however, may be used successfully in the present invention, for example, certain copolymers of vinyl chloride and acrylonitrilei Referring now to the drawings wherein preferred em-' bodiments of my invention are shown,- .Figure,1 shows staple, and potentially adhesive or thermoplastic fibers. The fibers mentioned above are of the textile fiber the fibrous element'in bundle or sliver form. As seen therein, the sliver A is a carefully blended mixture of non-adhesive regenerated cellulose fibers, suchas rayon class having diameters of at least 9 microns.

The mixture of the present invention can .be. satisfactorily formed .by uniformly distributing 10-25% of the potentially adhesive fibers into the major proportion,

ZS- 90% by weight, of crimped rayon staple fiber. 'It

has been found tha t the potentially adhesive fibers should comprise at least 10% by Weight of the mixture and preferably should be in the range off20% by weight] I The length. of the individual fibers, both potentially fad- Patented Apr. 1 1, 1951 hesive and non-adhesive, may vary from to 2 /2 inches and should be between 1 to 2 /2 denier, preferably 1 to 1 /2 denier. Due to the crimp in the non-adhesive fibers and, if desired,'in the potentially adhesive fibers, minute traps or voids are formed within the body of the element which enhance the absorptiveness of the element and also provide for the porosity which in turn permits easy draw.

The fibers specified above range in weight from 100- 125 grains and the fine relatively short length fibers provide a compact, dense structure in which many of the shorter length fibers will be across the' general longitudinal axis of the element.

An important feature of my invention is that the nonadhesive or rayon fibers within the fibrous mass are crimped. In the case of rayon, the fibers'may be crimped chemically as distinguished from a mechanical crimp. Such chemical crimping is disclosed and claimed in United States Patent 2,517,694. This crimping remains in the fiber even when it is wet. The filaments, however, may be mechanically crimped according to well known processes and apparatus. Since relatively small denier fibers are used to form the element and since the fibers are crimped, numerous minute traps or voids are formed within the element which render the fibrous element capable of entrapping and retaining liquids, moisture and minute solid particles. The potentially adhesive fibers may or may not be crimped. When converting the fibrous sliver to specific articles of use, the potentially adhesive fibers are activated, as will be explained hereinafter, to autogenously bond together the non-adhesive fibers in the sliver A. The fibers are compressed, as will also be explained, after the potentially adhesive fibers have been activated to provide a compact article of good strength.

A tobacco smoke filter'or plug B formed from the fibrous mass or sliver A of Figure l is shown in Figure 2 of the drawing. The tobacco smokefilter B, in this instance, is of cylindrical shape. The potentially adhesive fibers have been activated and compressed to autogenously bond together the non-adhesive rayon fibers and the potentially adhesive fibers to provide a compact cylindrical shaped article of good strength. When .the completed element is to be used as a cigarette filter, the bonded element is wrapped or stuffed in a paper wrapper 2 and cut into suitable lengths to form the filter plug B.

Figure 3 shows the wrapped filter plug'B of .Figure 2 incorporated in a cigarette C. The tobacco -and the filter plug B are formed into a unitary cigarette having the usual cigarette paper 11.

The apparatus'in which the relatively loose sliver isactivated and transformed into a comparatively strong, dense but porous rod comprises a chamber18 into which the sliver 19'is drawn through a funnel shaped die 20 mounted in the forward end wall 21 of the chamber. The tacky sliver is drawn out of the chamber 18 through a relatively longer die 23 mounted in the rear wall 24 of the chamber in alignment with die 20. Die 23 has a substantially smaller bore than entrance die 20. The preferred diameters for the entrance and exit dies are threequarters and three-eighths of an inch respectively when it is desired to fabricate a cigarette filter. For other articles the dimension of the bores may be changed but substantially the same ratio should be maintained. The inside ofthe chamber 18 is maintained at an elevated temperature of approximately 180 C. by means of one or more heating elements 25, '25 'whichsurround the walls of the chamber. If desired, the heating elements are covered by suitable insulating material 27 through which electrical connections to the heaters may be made at 28, 28. At a point approximately midway between the downstream terminus of die 20' and the upstream terminus of die 23, a liquid-softening or activatingagent such as acetone is introduced in drop.forrn'"into thel charn' ber through a nozzle 30. Theacetone is vaporized when it falls onto the heated chamber wall. As the vapor contacts the potentially adhesive fibers in the sliver, they become sufficiently soft throughout the sliver so that when the sliver is drawn through die 23 there is a compression or rearrangement of the structure to provide a firm, compact, internally bound but porous rod 31. The potentially adhesive fibers set up after leaving die 23 when they are cooled and the acetone evaporates or is otherwise removed. Partial setting up may take place in the bore of die 23 and the length and relative axial position of this forming die in the end wall 24 is so controlled to provide the results which may be desired. In order to eliminate stocking or deposition of material in the bore of either of the dies, they are preferably made of polytetrafluoroethylene, sold commercially under the trade name of Teflon.

Depending upon the degree of activation found desirable and the speed with which the sliver is drawn through chamber 18- by means, of draw rolls R, R, it vmay be found necessary or desirable to provide limited venting for the chamber. This can be accomplished'by the provision of one or more flats 35, 35 (Figure 5 along the side of the entrance die 20. These flats extend through the end wall 21 so that limited venting of the interior of chamber 18 is achieved. By providing an annular bevel 4t? on thedo-wnstream .end of die 20, it ispossible to prevent build-up or adherence of fibers to any part of die 20.

Vaporized acetone as an activating agent for the potentially adhesive fibers is preferred in that it has been found that the fibers within the sliver 19 which have been subjected to vaporized acetoneare more firmly bonded together and the finished filter .plug exhibits greater stiffness and excellent draw properties which features also contribute to the success of the filter. .It has also been found that thecleaner cuts may be made with the acetone activated filter plug. In the apparatus described above, the softening of the potentially adhesive fibers is achieved primarily by means of the solvent, namely, acetone, which is applied to the fibers. However, it will be understood that the temperature in chamber 18 may be sufiiciently'elevated to assist or, if desired, completely provide for the softening of the minor proportion fibers.

As shown in Figure 6 of the drawings, a continuous filter rod 31 is collected in wound package form on a suitable wind-up spool 70 immediately after it has set up after being discharged from the chamber 18. .As the filter rod 31 is wound up in package form by the filter producer and while it is shipped to the cigarettee manufacturer/the original shape of the rod 31 is deformed into a flattened or otherwise distorted condition because of the tension applied during the windingoperation and because of the compressive force applied by the outer coils of la ers of the rod upon the inner coils of layers of the rod.

After the rod 31 is received by the cigarette manufacturer in wound packageform, it has to be restored to its original cylindrical shape. Figure 7 shows a reshaping device which may be used by the cigarette manufacturer to restore the continuous flattened rod 31 to its original cylindrical shape. As seen in Figure 7, the continuous filter rod 31 is unwound from its coiled package formed on the wind-upspool 70 and is fed into the reshaping device 72. The reshaping device 72 comprises an enclosedchamber 74 into which a moist heated fluid medium such as steam is introduced throughjinlet 76. The

continuous ro d31 is fed into the chamber through an entrance die 78 which extends through an end wal1 80 of the reshaping device 72. To restore the shape of the rod 31 to its original cylindrical shape, the rod passes through a shaping dieSZ which. extends through the opposite wall of the shaping device 72. As seen'in Figure 8, the shaping die 82 has a bore of cylindrical shape.

An external layer. of insulation material 84 fitted around the "periphery of thereshaping device 72 and a pressure gage 86 extends through the insulation layer 84 and the wall of the enclosed chamber 74 to record the pressure within the chamber 74. Condensed steam is discharged from the chamber 74 through an outlet 88 also extending through, the wall of chamber 74.

Figure 9 shows the flattened condition of the filter rod 31 before it is introduced into the reshaping device 72 while Figure 10 shows the rod 31 restored to its original cylindrical shape after it has been discharged from the reshaping device 72.

As the rod 31 travels through the chamber 74, the heat from the steam softens the potentially adhesive fibers in the rod 31 while the moisture softens the nonadhesive fibers within the rod 31. With the fibers in this malleable condition, the rod 31 is easily reshaped to its original cylindrical form as it passes through the shaping die 82.

The reshaping device 72 is retained by the cigarette manufacturer whereupon when the manufacturer is ready to incorporate the filter rod 31 with the tobacco cylinders to make filter cigarettes, he merely has to unwind the rod from its package form and pass it through the reshaping device 72. As the rod 31 is discharged from the reshaping device, it is fed directly into a filter wrapping apparatus (not shown) wherein a paper wrapper is secured around the rod 31. With the above described method, the cigarettee manufacturer need not clutter up his available space with apparatus for producing the filter material. This time, energy and available space may therefore be devoted entirely to the production of cigarettes. The outside filter material producer need not be concerned about the flattened condition of the filter rod in its packaged form since he knows that it can easily be restored to its original cylindrical shape by the cigarette manufacturer. 7

It is to be understood that changes and variations may be made without departing from the spirit and scope of the present invention as defined in the appended claims.

I claim:

1. The method of making a fibrous rod having the form of a circular cylinder comprising forming a loose sliver of non-adhesive and potentially adhesive fibers,

activating the potentially adhesive fibers, compressing the sliver into circular cylinder configuration to bring the fibers into intimate contact with one another whereby at least some of the potentially adhesive fibers adhere to at least some of the non-adhesive fibers and form a relatively stiif rod of fibers, winding the rod into a package whereby the rod is deformed from its circular cylinder configurations, unwinding the deformed rod, subjecting the unwound rod to the action of steam to soften the fibers, and drawing the rodwhile the fibers are still softened through a die to restore the circular cylinder configuration.

2. The method of producing a relatively stiif fibrous rod of circular cross-section suitable for use as a cigarette filter comprising forming a sliver of a mixture of nonadhesive and potentially adhesive fibers, passing the sliver through a chamber, activating the potentially adhesive fibers within the chamber with a vaporized activating agent, passing the sliver through a circular die to compress the fibers and form a fibrous cylinder of circular cross-section, permitting the activating agent to volatilize whereby a relatively stiff fibrous rod of circular crosssection results, winding the fibrous rod into a coil whereby the cross-section thereof is distorted, unwinding the rod and subjecting it to the action of steam to soften the fibers, drawing the rod while the fibers are in a softened condition through a circular die of substantially the same diameter as the previously mentioned die to restore the rod to the dimensions it had before being wound into a coil.

3. The method of claim 2 wherein the non-adhesive fibers are crimped viscose rayon and the potentially adhesive fibers are formed of a copolyrner of vinyl chloride and vinyl acetate.

References Cited in the file of this patent UNITED STATES PATENTS 2,483,406 Francis Oct. 4, 1949 2,661,499 James et al. Dec. 8, 1953 2,688,380 MacHenry Sept. 7, 1954 2,813,051 MacHeury Nov. 12, 1957 

1. THE METHOD OF MAKING A FIBROUS ROD HAVING THE FORM OF A CIRCULAR CYLINDER COMPRISING FORMING A LOOSE SILVER OF NON-ADHESIVE AND POTENTIALLY ADHESIVE FIBERS, ACTIVATING THE POTENTIALLY ADHESIVE FIBERS, COMPRESSING THE SILVER INTO CIRCULAR CYLINDER CONFIGURATION TO BRING THE FIBERS INTO INTIMATE CONTACT WITH ONE ANOTHER WHEREBY AT LEAST SOME OF THE POTENTIALLY ADHESIVE FIBERS ADHERE TO AT LEAST SOME OF THE NON-ADHESIVE FIBERS AND FORM A RELATIVELY STIFF ROD OF FIBERS, WINDING THE ROD INTO A PACKAGE WHEREBY THE ROD IS DEFORMED FROM ITS CIRCULAR CYLINDER CONFIGURATIONS, UNWINDING THE DEFORMED ROD, SUBJECTING THE UNWOUND ROD TO THE ACTION OF STEAM TO SOFTEN THE FIBERS, AND DRAWING THE ROD WHILE THE FIBERS ARE STILL SOFTENED THROUGH A DIE TO RESTORE THE CIRCULAR CYLINDER CONFIGURATION. 